## jadekelllly 2 years ago solve cos(2x-4)=sin(6x)

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what's interval for x ?

i have no clue, im doing the work sheet and that is all it says for this question

it says solve for x

4. dan815

|dw:1371573363440:dw|

5. dan815

remember complimentary angles

the answer choices are 20, -11, 10.75, or 11.75

7. dan815

if just in the 1st quadrant. u can use the identity : cosx = sin(90-x) cos(2x-4)=sin(6x) sin(90-(2x-4))=sin(6x) 90-(2x-4) = 6x solve for x the result would be same like @dan817 said :)

oppss 815 not 817, hihi :)

10. dan815

hi :)

11. dan815

do u see how complimentary angles work now

12. dan815

in a right angled triangle the 2 other angles must add up to 90

Im really slow at picking up these concepts.....:/ so this im reallly lost..

14. dan815

hmm how else can i explain it

16. dan815

no lets do it between 4 to pi+4 for 1 interval of your cos(2x-4)

hmmm.. for easier, solve this algebrically :) can u solve for x, this part : |dw:1371574314002:dw|

18. dan815

first solve an x that works and ill show u how u can find all the other xs that work

|dw:1371574763654:dw|

20. Vitas

cos(2x-4)=cos(90-6x) a)2x-4=90-6x+360k b)2x-4=6x-90+360k a)x=94/8+45k b)x=86/4+90k

21. Protien

x=11.75